Question: $ { \left[\begin{array}{rr}{0} & {1} \\ {-2} & {1}\end{array}\right]-\left[\begin{array}{rr}{0} & {-2} \\ {-2} & {4}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{0}-{0} & {1}-{-2} \\ {-2}-{-2} & {1}-{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {3} \\ {0} & {-3}\end{array}\right]}$